The present invention relates to a method for solubilizing polystyrene constituents in a fatty acid ester. The solubilized polystyrene fatty acid ester mixture can be used in a variety of polymeric applications including forming low cost mixed polymers.
Polystyrenes (C6H5CHCH2)n, which are also known as styrofoam, are transparent, hard, high strength and impact resistant polymers which are often used in electrical, vibrational, and thermal insulator applications. Additionally, polystyrenes are used in applications related to packaging, refrigerator doors, air conditioner cases, containers and molded household wares, boats, water coolers, and a variety of other uses. As can be seen, use of polystyrene is prevalent. Despite the prevalence of polystyrene, there are disadvantages associated with its use. Polystyrene does not readily degrade and typically cannot be reused. Consequently, waste polystyrene is typically disposed of in landfills as a solid waste. This is an undesired way of disposing of waste polystyrene, especially in view of a more environmentally conscious public. Polystyrene is a low density, high volume material, causing it to consume space in a landfill. As such, there is a desire to reduce the amount of polystyrene material placed in landfills, with it especially desired to have a method for reusing or recycling polystyrene. Because of their low density and high volume, polystyrenes are a special problem in landfills.
Previously, one method for reusing or disposing of waste polystyrenes involved dissolving such constituents in volatile organic compounds (VOCs). The VOC is any hydrocarbon, except methane and ethane, with a vapor pressure equal or greater than 0.1 mm Hg. After dissolution, the VOC and polystyrene mixture was then used as a constituent in finished polymeric products. Unfortunately, methods for disposing of polystyrenes which include VOCs are undesirable because such constituents are typically hazardous and present a variety of additional waste disposal problems. As such, it is desired to have a method for solublizing and reusing polystyrene that does not involve the use of a VOC or similar hazardous material. More particularly, it is desired to have a method or composition which can be used to solubilize polystyrene that is not hazardous and can be readily used in a variety of applications.
The present invention relates to a method for solubilizing polystyrene, wherein the method involves placing polystyrene in an amount of a liquid fatty acid ester, with the fatty acid ester preferably heated. The fatty acid ester will cause the polystyrene to liquify and form a polystyrene fatty acid ester mixture. If the fatty acid ester is heated, the polystyrene will liquify faster. The present invention also relates to the polystyrene fatty acid ester composition that can be mixed with a polyester to form an improved polymeric composition.
As alluded to above, the present method includes heating the fatty acid ester to a temperature sufficient to cause the polystyrene to rapidly solubilize in the heated fatty acid ester. Solubilization can occur at ambient temperatures but at a slower rate. Also, temperatures can vary dependent upon the conditions associated with the step of heating the fatty acid ester. Such conditions include the pressure and whether the mixture is stirred.
The fatty acid ester can be selected from any of a variety of fatty acids that have been esterified. It is preferred, however, if the fatty acid portion of the fatty acid ester is a long chain fatty acid. Any fatty acid ester can be used so long as the polystyrene can be solubilized in the oil and the resultant mixture can be used in various polymeric applications. It is preferred if the polystyrene is added to the oil in an amount equal to between 1% and 80% by weight of the fatty acid ester. Also, it is most preferred if the fatty acid ester is a methyl soyate.
The present invention is advantageous for a number of reasons. Most importantly, the present invention is an environmentally friendly method for reusing polystyrene. Further, the present invention is advantageous because a method is developed that allows for reuse of the polystyrene, whereby disposal in a landfill is substantially eliminated. Another advantage related to the polystyrene fatty acid ester composition includes mixing with a polyester to form an improved polymeric composition.